1. Field of the Invention
The present invention relates to a semiconductor device and a method for making the same, and, in particular, to the field of a semiconductor device of a trench-gate type MOSFET and a method for making the same.
2. Description of the Related Art
MOS-type transistors, such as power MOSFETs (Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors), have been used as a semiconductor device for power control. In these semiconductor devices, it is required to have a reduced power loss and a lower capacitance characteristic in switching operation. A trench-gate structure is known to meet such needs, as disclosed in Japanese Patent Laid-Open No. 2003-92405.
When a semiconductor chip is actually made that includes a MOS-type transistor with such a trench-gate structure, a trench gate, a terminal-embedded insulation layer and a trench contact should be formed. In order to form these components, photolithography should be performed about 10 times, which results in increased cost due to the time consuming and expensive procedures.